An example of coaxial two-wheel vehicles in the related art is disclosed in Patent Document 1. Patent Document 1 proposes a coaxial two-wheel vehicle having a vehicle structure in which a user gets on the vehicle in a standing posture. In the coaxial two-wheel vehicle disclosed in Patent Document 1, operations such as forward/backward movements and left/right turns are performed in response to instructions resulting from movement of a handle, movement of the center of gravity of a passenger, inclination of a step on which the passenger rides, and the like, thereby steering the vehicle. Further, this coaxial two-wheel vehicle is unstable in a front-and-rear direction because of its structure, like other common coaxial two-wheel vehicles. Accordingly, wheels of the vehicle are controlled through feedback control by using a posture sensor to thereby stabilize the vehicle.    [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2006-315666